Efficient communication of network identifiers

ABSTRACT

in the context of “operator-controlled Wi-Fi” as in 3GPP TR 37,834 v12,0,0 “Study on Wireless Local Area Network (WLAN)”, both in solution2 and solution3, WLAN identifiers need to be communicated between the radio access network, RAN, and the UE. However, WLAN identifiers (e.g., SSIDs, BSSIDs, ESSIDs, HESSIDs, Realm identifiers, NAIs, PLMN identifiers, Domain Name lists, . . . ) are large (e.g., SSID may be up to 32 bytes) and cause a large overhead in the wireless interface. This problem is solved by providing an indexed listing of WLAN Identifiers and by only exchanging the indices across the wireless interface; Preferably, some WLANs may have several indices, and each index may also be used to convey the action to take by the UE.

TECHNICAL FIELD

The techniques described herein relate to the communication of networkidentifiers, for example identifiers of wireless local area networks,WLANs, between a terminal device and a network node, or between networknodes.

BACKGROUND

The wireless local-area network (WLAN) technology known as “Wi-Fi” hasbeen standardized by IEEE in the 802.11 series of specifications (i.e.,as “IEEE Standard for Information technology—Telecommunications andinformation exchange between systems. Local and metropolitan areanetworks—Specific requirements. Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications”).

Cellular operators that are currently serving mobile users with, forexample, any of the technologies standardized by the 3rd-GenerationPartnership Project (3GPP), including the radio-access technologiesknown as Long-Term Evolution (LTE), Universal Mobile TelecommunicationsSystem (UMTS)/Wideband Code-Division Multiple Access (WCDMA), High SpeedPacket Access (HSPA) and Global System for Mobile Communications (GSM),see Wi-Fi as a wireless technology that can provide good additionalsupport for users in their regular cellular networks. There is interestaround using the Wi-Fi technology as an extension, or alternative tocellular radio access network technologies to handle the alwaysincreasing wireless bandwidth demands. The term “operator-controlledWi-Fi” points to a Wi-Fi deployment that on some level is integratedwith a cellular network operator's existing network and where the 3GPPradio access networks and the Wi-Fi wireless access may even beconnected to the same core network and provide the same services.

3GPP is currently working on specifying a feature/mechanism forWLAN/3GPP Radio interworking which improves operator control withrespect to how a UE performs access selection and traffic steeringbetween 3GPP and WLANs belonging to the operator or its partners. Threedifferent solutions have been described in 3GPP TR 37.834 v12.0.0(2013-12) “Study on Wireless Local Area Network (WLAN) 3GPP radiointerworking (Release 12)”.

In one of the solutions (Solution 2 in TR 37.834), which is alsoreferred to as the “threshold-based mechanism” herein, the 3GPP network(i.e. network node of the first RAT) provides to the UE (the term usedto refer to a terminal device by 3GPP) conditions and/or thresholdswhich are used by the UE in one or more pre-defined rules dictating whenthe terminal device should steer traffic from one RAT to the other.

In another one of the solutions (Solution 3 in TR 37.834), which is alsoreferred to a “traffic steering command based mechanism” herein, the(3GPP) network configures the UE to send measurement reports related toWLANs the terminal device has discovered (or to WLANs for which certainconditions have been fulfilled). The network would, based on thesemeasurement reports, decide whether the terminal device shall steertraffic towards the reported WLANs. If a terminal device is to steertraffic towards a WLAN, the network sends a traffic steering command tothat terminal device.

In both of the above solutions, identifiers of WLANs (also referred toas WLAN identifiers) may need to be communicated between the radioaccess network, RAN, and the UE. In the threshold-based mechanism, theRAN may communicate a list of WLAN identifiers to the UE that areacceptable for the UE to consider when evaluating the pre-defined rules.In the traffic steering command based mechanism, the RAN may communicatea list of WLAN identifiers to the UE that the UE is to measure, and theUE may communicate the identity of one or more WLANs (i.e. the WLANidentifiers) that fulfill the conditions to the RAN.

WLAN identifiers are large, for example, a Service Set Indicator (SSID)may be up to 32 bytes. The communication of the WLAN identifiers betweenthe RAN and UE (and between nodes in the network in the event that theWLAN identifier list is provided from one node to another) can thereforegenerate a lot of signaling between the network and the UE just toidentify WLANs. This signaling will decrease system capacity, increaseterminal device power consumption, generate interference, etc.

A similar problem exists for other types of WLAN identifiers, such basicSSIDs, BSSIDs, extended SSIDs, ESSIDs, homogenous ESSIDs, HESSIDs, Realmidentifiers, Network Access Indicators, NAIs, public land mobilenetwork, PLMN, identifiers, or Domain Name lists, as well as identifiersfor networks operating according to other radio access technologies(RATs).

It will be appreciated that these problems are not confined to thecommunication of network identifiers as part of an interworkingmechanism, and that they can arise in other situations where one or morenetwork identifiers are communicated between a UE and network node (orbetween network nodes).

Therefore, there is a need for a technique for the efficientcommunication of network identifiers, for example identifiers of WLANs,between a terminal device and a network node, or between network nodes.

SUMMARY

According to a first aspect, there is provided a method of operating aterminal device, the method comprising maintaining one or more indicesand a mapping between the one or more indices and respective networkidentifiers, each network identifier identifying a network and/or anetwork node; and in communications between the terminal device and afirst network in which a particular network and/or a particular networknode is to be identified, using the index associated with the particularnetwork and/or the particular network node to identify the particularnetwork and/or the particular network node.

According to a second aspect, there is provided a terminal device,wherein the terminal device is adapted to maintain one or more indicesand a mapping between the one or more indices and respective networkidentifiers, each network identifier identifying a network and/or anetwork node; and use the index associated with the particular networkand/or the particular network node to identify the particular networkand/or the particular network node in communications between theterminal device and a first network in which a particular network and/ora particular network node is to be identified.

According to a third aspect, there is provided a method of operating anetwork node in a first network, the method comprising maintaining oneor more indices and a mapping between the one or more indices andrespective network identifiers, each network identifier identifying anetwork and/or a network node; and in communications between the networknode and a terminal device or other network node in which a particularnetwork and/or a particular network node is to be identified, using theindex associated with the particular network and/or the particularnetwork node to identify the particular network and/or the particularnetwork node.

According to a fourth aspect, there is provided a network node for usein a first network, wherein the network node is adapted to maintain oneor more indices and a mapping between the one or more indices andrespective network identifiers, each network identifier identifying anetwork and/or a network node; and use the index associated with theparticular network and/or the particular network node to identify theparticular network and/or the particular network node in communicationsbetween the network node and a terminal device or other network node inwhich a particular network and/or a particular network node is to beidentified.

According to a fifth aspect, there is provided a method of operating anetwork node in a first network, the method comprising determining oneor more indices and a mapping between the one or more indices andrespective network identifiers, each network identifier identifying anetwork and/or a network node; and sending the one or more indices andthe mapping to another network node in the first network or to aterminal device in the first network.

According to a sixth aspect, there is provided a network node for use ina first network, the network node being adapted to determine one or moreindices and a mapping between the one or more indices and respectivenetwork identifiers, each network identifier identifying a networkand/or a network node; and send the one or more indices and the mappingto another network node in the first network or to a terminal device inthe first network.

According to a seventh aspect, there is provided a computer programproduct comprising a computer readable medium having computer readablecode embodied therein, the computer readable code being configured suchthat, on execution by a suitable computer or processor, the computer orprocessor is caused to perform any of the above method embodiments.

According to an eighth aspect, there is provided a terminal device thatcomprises a processor and a memory, said memory containing instructionsexecutable by said processor whereby said terminal device is operativeto maintain one or more indices and a mapping between the one or moreindices and respective network identifiers, each network identifieridentifying a network and/or a network node; and use the indexassociated with the particular network and/or the particular networknode to identify the particular network and/or the particular networknode in communications between the terminal device and a first networkin which a particular network and/or a particular network node is to beidentified.

According to a ninth aspect, there is provided a network node for use ina first network, the network node comprising a processor and a memory,said memory containing instructions executable by said processor wherebysaid network node is operative to maintain one or more indices and amapping between the one or more indices and respective networkidentifiers, each network identifier identifying a network and/or anetwork node; and use the index associated with the particular networkand/or the particular network node to identify the particular networkand/or the particular network node in communications between the networknode and a terminal device or other network node in which a particularnetwork and/or a particular network node is to be identified.

According to a tenth aspect, there is provided a network node for use ina first network, the network node comprising a processor and a memory,said memory containing instructions executable by said processor wherebysaid network node is operative to determine one or more indices and amapping between the one or more indices and respective networkidentifiers, each network identifier identifying a network and/or anetwork node; and send the one or more indices and the mapping toanother network node in the first network or to a terminal device in thefirst network.

According to an eleventh aspect, there is provided a terminal device,the terminal device comprising a first module for maintaining one ormore indices and a mapping between the one or more indices andrespective network identifiers, each network identifier identifying anetwork and/or a network node; and a second module for using the indexassociated with the particular network and/or the particular networknode to identify the particular network and/or the particular networknode in communications between the terminal device and a first networkin which a particular network and/or a particular network node is to beidentified.

According to a twelfth aspect, there is provided a network node for usein a first network, wherein the network node comprises a first modulefor maintaining one or more indices and a mapping between the one ormore indices and respective network identifiers, each network identifieridentifying a network and/or a network node; and a second module forusing the index associated with the particular network and/or theparticular network node to identify the particular network and/or theparticular network node in communications between the network node and aterminal device or other network node in which a particular networkand/or a particular network node is to be identified.

According to a thirteenth aspect, there is provided a network node foruse in a first network, the network node comprising a first module fordetermining one or more indices and a mapping between the one or moreindices and respective network identifiers, each network identifieridentifying a network and/or a network node; and a second module forsending the one or more indices and the mapping to another network nodein the first network or to a terminal device in the first network.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the techniques introduced in this document aredescribed below with reference to the following figures, in which:

FIG. 1 is a non-limiting example block diagram of an LTE cellularcommunications network;

FIG. 2 is a block diagram of a terminal device according to anembodiment;

FIG. 3 is a block diagram of a radio access network node according to anembodiment;

FIG. 4 is a block diagram of a core network node according to anembodiment;

FIG. 5 is a block diagram of a WLAN access point according to anembodiment;

FIG. 6 illustrates a method of operating a terminal device according toan embodiment;

FIG. 7 illustrates a method of operating a network node according to anembodiment;

FIG. 8 illustrates another method of operating a network node accordingto an exemplary embodiment;

FIG. 9 is a diagram illustrating one example of a network interworkingfeature; and

FIG. 10 is a flow chart illustrating a specific embodiment of thetechniques described herein.

DETAILED DESCRIPTION

The following sets forth specific details, such as particularembodiments for purposes of explanation and not limitation. But it willbe appreciated by one skilled in the art that other embodiments may beemployed apart from these specific details. In some instances, detaileddescriptions of well known methods, nodes, interfaces, circuits, anddevices are omitted so as not obscure the description with unnecessarydetail. Those skilled in the art will appreciate that the functionsdescribed may be implemented in one or more nodes using hardwarecircuitry (e.g., analog and/or discrete logic gates interconnected toperform a specialized function, ASICs, PLAs, etc.) and/or using softwareprograms and data in conjunction with one or more digitalmicroprocessors or general purpose computers. Nodes that communicateusing the air interface also have suitable radio communicationscircuitry. Moreover, the technology can additionally be considered to beembodied entirely within any form of computer-readable memory, such assolid-state memory, magnetic disk, or optical disk containing anappropriate set of computer instructions that would cause a processorand also in some cases a receiver component and/or transmitter componentto carry out the techniques described herein.

Hardware implementation may include or encompass, without limitation,digital signal processor (DSP) hardware, a reduced instruction setprocessor, hardware (e.g., digital or analog) circuitry including butnot limited to application specific integrated circuit(s) (ASIC) and/orfield programmable gate array(s) (FPGA(s)), and (where appropriate)state machines capable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors, one or more processing units, one ormore processing modules or one or more controllers, and the termscomputer, processor, processing unit, processing module and controllermay be employed interchangeably. When provided by a computer, processor,processing unit, processing module or controller, the functions may beprovided by a single dedicated computer, processor, processing unit,processing module or controller, by a single shared computer, processor,processing unit, processing module or controller, or by a plurality ofindividual computers, processors, processing units, processing modulesor controllers, some of which may be shared or distributed. Moreover,the terms “processor”, “processing unit”, “processing module” or“controller” also refer to other hardware capable of performing suchfunctions and/or executing software, such as the example hardwarerecited above.

Although the description is given for a terminal device or userequipment (UE), it should be understood by the skilled in the art that“terminal device” and “UE” are non-limiting terms comprising any mobile,non-mobile or wireless device or node equipped with a radio interfaceallowing for at least one of: transmitting signals in uplink (UL) andreceiving and/or measuring signals in downlink (DL). A UE herein maycomprise a UE (in its general sense) capable of operating or at leastperforming measurements in one or more frequencies, carrier frequencies,component carriers or frequency bands. It may be a “UE” operating insingle- or multi-radio access technology (RAT) or multi-standard mode.As well as “UE” and “terminal device”, the term “mobile device” is usedinterchangeably in the following description, and it will be appreciatedthat such a device does not necessarily have to be mobile in the sensethat it is carried by a user. Instead, the term “mobile device”, as with“terminal device” encompasses any device that is capable ofcommunicating with communication networks that operate according to oneor more mobile communication standards, such as GSM, UMTS, LTE, etc.

A cell is associated with a radio access network (RAN) node, where a RANnode comprises in a general sense any node transmitting radio signals inthe downlink (DL) to a terminal device and/or receiving radio signals inthe uplink (UL) from a terminal device. Some example RAN nodes, or termsused for describing RAN nodes, are base station, eNodeB, eNB, NodeB,macro/micro/pico/femto radio base station, home eNodeB (also known asfemto base station), relay, repeater, sensor, transmitting-only radionodes or receiving-only radio nodes. A RAN node may operate or at leastperform measurements in one or more frequencies, carrier frequencies orfrequency bands and may be capable of carrier aggregation. It may alsobe a single-radio access technology (RAT), multi-RAT, or multi-standardnode, e.g., using the same or different base band circuitry fordifferent RATs.

It should be noted that unless otherwise indicated, the use of thegeneral term “network node” as used herein refers to a RAN node, such asa base station, an eNodeB, a network node in the RAN responsible forresource management, such as a radio network controller (RNC), a corenetwork node, such as a mobility management entity (MME) or servinggateway (SGW), or a WLAN Access Point (AP).

The signalling described is either via direct links or logical links(e.g. via higher layer protocols and/or via one or more network nodes).For example, signalling from a coordinating node may pass anothernetwork node, e.g., a radio node.

FIG. 1 shows an example diagram of an evolved UMTS Terrestrial RadioAccess Network (EUTRAN) architecture as part of an LTE-basedcommunications system 2. Nodes in the core network 4 include one or moreMobility Management Entities (MMEs) 6, a key control node for the LTEaccess network, and one or more Serving Gateways (SGWs) 8 which routeand forward user data packets while acting as a mobility anchor. Theycommunicate with base stations 10 in the RAN referred to in LTE as eNBsor eNodeBs, over an interface, for example an S1 interface. The eNBs 10can include the same or different categories of eNBs, e.g. macro eNBs,and/or micro/pico/femto eNBs. The eNBs 10 communicate with each otherover an interface, for example an X2 interface. The S1 interface and X2interface are defined in the LTE standard. A UE 12 can receive downlinkdata from and send uplink data to one of the base stations 10 with thatbase station 10 being referred to as the serving base station of the UE12. An access point (AP) 14 that is part of a WLAN is also shown in FIG.1, although it will be appreciated that the WLAN and AP 14 are not partof the EUTRAN architecture.

FIG. 2 shows a terminal device 12 or user equipment (UE) that can beadapted for use in one or more of the non-limiting example embodimentsdescribed. The terminal device 12 comprises a processing unit 30 thatcontrols the operation of the terminal device 12. The processing unit 30is connected to a receiver or a transceiver 32 (which comprises areceiver and a transmitter) with associated antenna(s) 34 which are usedto receive signals from or both transmit signals to and receive signalsfrom one or more different types of radio access network (e.g. two ormore radio access networks that are operating according to differentradio access technologies, RATs), such as RAN node 10 in the LTE network2 and access point (AP) 14 in a WLAN. The terminal device 12 alsocomprises a memory unit 36 that is connected to the processing unit 30and that stores computer program code and other information and datarequired for the operation of the terminal device 12.

FIG. 3 shows a RAN node 10 (for example a base station, NodeB or aneNodeB) that can be adapted for use in example embodiments described.The RAN node 10 comprises a processing unit 40 that controls theoperation of the base station 10. The processing unit 40 is connected toa transmitter or a transceiver 42 (which comprises a receiver and atransmitter) with associated antenna(s) 44 which are used to transmitsignals to, and receive signals from, terminal devices 12 in the network2. The RAN node 10 also comprises a memory unit 46 that is connected tothe processing unit 40 and that stores computer program code and otherinformation and data required for the operation of the RAN node 10. TheRAN node 10 also includes components and/or circuitry 48 for allowingthe RAN node 10 to exchange information with other RAN nodes 10 (forexample via an X2 interface) and components and/or circuitry 49 forallowing the RAN node 10 to exchange information with nodes in the corenetwork 4 (for example via the S1 interface). It will be appreciatedthat RAN nodes for use in other types of network (e.g. UTRAN or WCDMARAN) may include similar components to those shown in FIG. 3 and may, ifappropriate, include interface circuitry 48, 49 for enablingcommunications with the other network nodes in those types of networks(e.g. other base stations, mobility management nodes and/or nodes in thecore network).

FIG. 4 shows a core network node 6, 8 that can be adapted for use in theexample embodiments described. The node 6, 8 comprises a processing unit50 that controls the operation of the node 6, 8. The processing unit 50is connected to components and/or circuitry 52 for allowing the node 6,8 to exchange information with RAN nodes 10 with which it is associated(which is typically via the S1 interface). The node 6, 8 also comprisesa memory unit 56 that is connected to the processing unit 50 and thatstores computer program code and other information and data required forthe operation of the node 6, 8.

FIG. 5 shows a WLAN AP 14 that can be adapted for use in the exampleembodiments described. The AP 14 comprises a processing unit 60 thatcontrols the operation of the AP 14. The processing unit 60 is connectedto a transmitter or a transceiver 62 (which comprises a receiver and atransmitter) with associated antenna(s) 64 which are used to transmitsignals to, and receive signals from, terminal devices 12. The AP 14also comprises a memory unit 66 that is connected to the processing unit60 and that stores computer program code and other information and datarequired for the operation of the AP 14. The AP 14 also includescomponents and/or circuitry 68 for connecting the AP 14 to a telephoneline or other broadband connection.

It will be appreciated that only the components of the terminal device12, RAN node 10, core network node 6, 8 and AP 14 that are useful toexplain the embodiments presented herein are illustrated in FIGS. 2, 3,4 and 5.

As noted above, it is often useful or required to communicate networkidentifiers, which identify a particular network or a particular networknode (such as an eNB or WLAN AP), between a terminal device and anetwork node, or between network nodes.

These network identifiers can include identifiers used in WLANs (i.e.WLAN identifiers), such as a Service Set Indicator (SSID), a basic SSID,BSSID, an extended SSID, ESSID, a homogenous ESSID, HESSID, a Realmidentifier, a Network Access Indicator, NAI, a public land mobilenetwork, PLMN, identifier, or a Domain Name list, as well as identifiersfor networks operating according to other radio access technologies(RATs). It will be appreciated that some network identifiers identifyboth a network and a particular network node. For example a HESSIDidentifies both a network and a particular WLAN. A HESSID is the BSSIDof a certain WLAN AP in a group of APs, and the BSSID of this selectedWLAN AP is also used to identify the group of APs.

Since these network identifiers can be quite large, for example, aService Set Indicator (SSID) may be up to 32 bytes, and it may often benecessary to communicate a number of network identifiers, it isdesirable for there to be a technique for the efficient communication ofnetwork identifiers between a terminal device and a network node orbetween network nodes, in order to minimise the signalling required andavoid unnecessarily decreasing system capacity, increasing terminaldevice power consumption and generating interference.

Thus according to the techniques described herein, to reduce the amountof signaling between the network node and the terminal device (andbetween network nodes) an identifier-to-index mapping is introduced sothat the indices can be signaled instead of explicitly signaling thenetwork identifiers.

In this technique, a mapping between network identifiers and indices isdetermined. This mapping can be determined by a network node in theradio access network (RAN) or core network (CN), such as aneNB/RNC/MME/etc. The network node can then signal this mapping to aterminal device and/or other network nodes (e.g. from a CN node to oneor more RAN nodes, or from a RAN node to other RAN nodes). The indicesprovided by the mapping can then be used in communications between thenetwork and the terminal device or between network nodes, which avoidhaving to use the network identifiers themselves in the communications.The indices act as a ‘common language’ between the network and theterminal or between the network nodes.

FIG. 6 illustrates an exemplary method of operating a terminal deviceaccording to the techniques described herein. Thus, in a first step,step 101, the terminal device 12 maintains one or more indices and amapping between the one or more indices and respective networkidentifiers. Each of the network identifiers identifies a network and/ora network node. The indices and mapping can be maintained by storingthem in the memory unit 36 of the terminal device 12 or reading themfrom broadcast or dedicated signalling from the network.

The network identifiers preferably relate to network(s) and/or networknodes in a network other than the first network 2 (although in someembodiments they can relate to network nodes in the same network). Thenetwork and/or network nodes can be operating according to the same or adifferent RAT to the first network 2.

The indices and mapping maintained in step 101 may have been receivedfrom the first network 2. In other embodiments, the terminal device 12may receive a list and/or sequence of network identifiers from the firstnetwork 2 and determine the one or more indices and the mapping based onthe position of each network identifier in the received list and/orsequence.

Embodiments relating to the form of the indices and mapping aredescribed in more detail below.

After maintaining (e.g. storing or reading) the one or more indices andthe mapping, in communications between the terminal device 12 and afirst network 2 in which a particular network or a particular networknode (e.g. WLAN AP 14) is to be identified, the terminal device 12 usesthe index associated with the particular network and/or the particularnetwork node to identify the particular network and/or the particularnetwork node (step 103). As described in more detail below, thesecommunications can comprise downlink communications from the firstnetwork 2 that include an index or indices relating to one or morenetworks and/or network nodes to be identified to the terminal device12, uplink communications from the terminal device 12 to the firstnetwork 2 that include an index or indices relating to one or morenetworks and/or network nodes to be identified to the first network 2,or both uplink and downlink communications.

FIG. 7 illustrates an exemplary method of operating a network node 10 ofa first network 2 according to the techniques described herein. Thenetwork node may be a node in the RAN of the first network (in whichcase the network node can be an eNB, RNC or WLAN AP). In a first step,step 111, the network node 10 maintains one or more indices and amapping between the one or more indices and respective networkidentifiers. Each of the network identifiers identifies a network and/ora network node (e.g. an eNB or WLAN AP). The indices and mapping can bemaintained by storing them in the memory unit 46 of the network node 10.

The network identifiers preferably relate to network(s) and/or networknodes in a network other than the first network 2 (although in someembodiments they can relate to network nodes in the same network). Thenetwork and/or network nodes can be operating according to the same or adifferent RAT to the first network 2.

The indices and mapping maintained in step 111 may have been receivedfrom a network node 6 in the core network 4 the first network 2 oranother network node 10 in the RAN. In other embodiments, the networknode 10 may determine the one or more indices and mapping from a listand/or sequence of network identifiers.

Embodiments relating to the form of the indices and mapping aredescribed in more detail below.

After maintaining the one or more indices and mapping, in communicationsbetween the network node 10 and a terminal device 12 or another networknode 10 in which a particular network and/or a particular network nodeis to be identified, the network node 10 uses the index associated withthe particular network and/or the particular network node to identifythe particular network or the particular network node (step 113). Asdescribed in more detail below, these communications can comprisedownlink communications from the network node 10 to the terminal device12 that include an index or indices relating to one or more networksand/or network nodes to be identified to the terminal device 12, uplinkcommunications from the terminal device 12 to the network node 10 thatinclude an index or indices relating to one or more networks and/ornetwork nodes to be identified to the first network 2 by the terminaldevice 12, or both uplink and downlink communications.

In some embodiments, a network node may be responsible for determiningthe one or more indices and mapping and providing these to other networknodes. A method of operating a network node according to this embodimentis shown in FIG. 8. This method may be performed in a RAN node 10, suchas an eNB, RNC or WLAN AP, or a node 6 in the core network 4, such as anMME.

Thus, in step 121, the network node 6 determines one or more indices anda mapping between the one or more indices and respective networkidentifiers. Each of the network identifiers identifies a network and/ora network node (e.g. an eNB or WLAN AP).

The network identifiers may relate to network(s) and/or network nodes ina network other than the network in which the network node 6 isoperating, but in other embodiments they can relate to network nodes inthe same network.

The network node 6 then sends the one or more indices and the mapping toa network node 10, for example in the RAN of the network, and/or to aterminal device 12 in the network (step 123).

In the following explanation of the techniques provided herein, thespecific example of WLAN identifiers is used, but it will be appreciatedthat the techniques described below are equally applicable to othertypes of network identifiers.

In the following various embodiments are described of how a network nodeassociates an index to a network (e.g. WLAN) identifier (which hereinwill be referred to as identifier-to-index mapping) are described, how anetwork node communicates these indices and the mapping to the terminaldevice or to another network node, and how the index can be used incommunications between the network node and the terminal devices toreduce signaling overhead.

As noted above the network node sending this mapping may be an eNB, NB,RNC or similar. As noted above in FIG. 8, in some embodiments onenetwork node assigns the indices to the identifiers and this assignmentis then used by other network nodes. For example, it will be describedbelow how an MME establishes the identifier to index mapping, and themapping is used by another network node such as an eNB in itscommunication with a terminal device.

Although the identifier-to-index mapping is not limited to use inspecific situations, protocols or mechanisms, the following descriptionof the identifier-to-index mapping relates to its use in a 3GPP/WLANinterworking mechanism. The interworking mechanism may relate to any oneor more of access network selection, traffic steering (where all of auser's traffic or a certain part of a user's traffic is steered to aparticular network) and aggregation (where a user's traffic may be splitbetween carriers with networks operating according to different RATs,e.g. a carrier to a WLAN and a carrier to a 3GPP network). Thus, oneexemplary use of the techniques is where a 3GPP network node (i.e. anetwork node in a 3GPP network), such as an eNB, signals WLANidentifiers to a terminal device. The eNB may associate an index orindices with the WLAN identifiers and signal this mapping to theterminal device. This mapping can then be used in communication betweenthe network and the terminal device by referring to the indices insteadof the WLAN identifiers.

Two exemplary interworking mechanisms in which the techniques can beapplied, the threshold-based mechanism and traffic steering commandbased mechanism mentioned above, are described in more detail below.These mechanisms/solutions are described in 3GPP TR 37.834 v12.0.0(2013-12) “Study on Wireless Local Area Network (WLAN) 3GPP radiointerworking (Release 12)” as Solutions 2 and 3 respectively.

Solution 2

As noted above, in the threshold based mechanism the 3GPP network (i.e.network node of the first RAT) provides to the UE conditions and/orthresholds which are used by the UE in one or more pre-defined rulesdictating when the terminal device should steer traffic from one RAT tothe other.

For example, a pre-defined rule could be of the form shown in Table 1where threshold1, threshold2, threshold3 and threshold4 are provided tothe UE by the 3GPP network, i.e. a network node of the first RAT such asan eNodeB, Node B or RNC.

TABLE 1 Example of the threshold based mechanism if (3GPP signal <threshold1) && (WLAN signal > threshold2) { steerTrafficToWLAN( ); }else if (3GPP signal > threshold3) || (WLAN signal < threshold4) {steerTrafficTo3gpp( ); }

This exemplary rule provides that if the UE measured 3GPP signal isbelow threshold1 and the UE measured WLAN signal is above threshold2then the terminal device steers traffic to WLAN. Otherwise, if the 3GPPsignal is above threshold3 and the WLAN signal is below threshold4 theterminal device steers traffic to 3GPP.

The term ‘3GPP signal’ herein could mean the signal transmitted by aradio network node belonging to a 3GPP RAT, e.g. a node in a LTE, HSPA,GSM etc. network, and/or it could be the quality of such a signal. Theterm ‘WLAN signal’ herein could mean the signal transmitted by a radionetwork node belonging to WLAN, e.g. an access point (AP) etc., and/orit could be the quality of such a signal. Examples of measurements of3GPP signals include are reference signal received power (RSRP) andreference signal received quality (RSRQ) in LTE or common pilot channel(CPICH) received signal code power (RSCP) and CPICH Ec/No in HSPA.Examples of measurements of WLAN signals are Received Signal StrengthIndicator (RSSI), Received Channel Power Indicator (RCPI), ReceivedSignal to Noise Indicator (RSNI), etc.

A high level description of this threshold based mechanism is providedbelow and also in 3GPP TS 36.300 v12.2.0.

23.6 Access Network Selection and Traffic Steering Between E-UTRAN andWLAN

This section describes the mechanisms to support traffic steeringbetween E-UTRAN and WLAN.

23.6.1 General Principles

This version of the specification supports E-UTRAN assisted UE basedbi-directional traffic steering between E-UTRAN and WLAN for UEs inRRC_IDLE and RRC_CONNECTED.

E-UTRAN provides assistance parameters via broadcast and dedicated RRCsignalling to the UE. The RAN assistance parameters may include E-UTRANsignal strength and quality thresholds, WLAN channel utilizationthresholds, WLAN backhaul data rate thresholds, WLAN signal strength andquality thresholds and Offload Preference Indicator (OPI). E-UTRAN canalso provide a list of WLAN identifiers to the UE via broadcastsignalling. WLANs provided by E-UTRAN may include an associatedpriority. The UE uses the RAN assistance parameters in the evaluationof:

-   -   Traffic steering rules defined in TS 36.304 [11]; or    -   ANDSF policies defined in TS 24.312 [58]

for traffic steering decisions between E-UTRAN and WLAN as specified inTS 23.402[19].

The OPI is only used in ANDSF policies as specified in TS 24.312 [58].

WLAN identifiers are only used in traffic steering rules defined in TS36.304 [11].

If the UE is provisioned with ANDSF policies it shall forward thereceived RAN assistance parameters to upper layers, otherwise it shalluse them in the traffic steering rules defined in section 23.6.2 and TS36.304 [11]. The traffic steering rules defined in section 23.6.2 and TS36.304 [11] are applied only to the WLANs of which identifiers areprovided by the E-UTRAN.

The UE in RRC_CONNECTED shall apply the parameters obtained viadedicated signalling if such have been received from the serving cell;otherwise, the UE shall apply the parameters obtained via broadcastsignalling.

The UE in RRC_IDLE shall keep and apply the parameters obtained viadedicated signalling, until cell reselection or a timer has expiredsince the UE entered RRC_IDLE upon which the UE shall apply theparameters obtained via broadcast signalling.

In the case of RAN sharing, each PLMN sharing the RAN can provideindependent sets of RAN assistance parameters.

23.6.2 Access Network Selection and Traffic Steering Rules

The UE indicates to upper layers when (and for which WLAN identifiersalong with associated priorities, if any) access network selection andtraffic steering rules defined in TS 36.304 [11] are fulfilled. Theselection among WLAN APs that fulfil the access network selection andtraffic steering rules is up to UE implementation.

When the UE applies the access network selection and traffic steeringrules defined in TS 36.304 [11], it performs traffic steering betweenE-UTRAN WLAN with APN granularity.

User preference takes precedence (FFS whether it does not apply toparticular scenarios).

Solution 3

As noted above, in the traffic steering command based mechanism, the(3GPP) network configures the terminal device to send measurementreports related to WLANs the terminal device has discovered (or to WLANsfor which certain conditions have been fulfilled). The network would,based on these measurement reports, decide whether the terminal deviceshall steer traffic towards the reported WLANs. If a terminal device isto steer traffic towards a WLAN, the network sends a traffic steeringcommand to that terminal device.

The following detailed description of this solution is also found insection 6.1.3 of TR 37.834:

In this solution the traffic steering for UEs in RRC CONNECTED/CELL_DCHstate is controlled by the network using dedicated traffic steeringcommands, potentially based also on WLAN measurements (reported by theUE).

For UEs in IDLE mode and CELL_FACH, CELL_PCH and URA_PCH states thesolution is similar to solution 1 or 2 [as described in TR 37.834],

Alternatively, UEs in those RRC [Radio Resource Control] states can beconfigured to connect to RAN and wait for dedicated traffic steeringcommands.

Overall Description—

As an example, traffic steering for UEs in RRC CONNECTED/CELL_DCHcomprises the following steps as shown in FIG. 9.

Step 201. Measurement control: The eNB/RNC configures the UE measurementprocedures including the identity of the target WLAN to be measured.

Step 202. Measurement report: The UE is triggered to send MEASUREMENTREPORT by the rules set by the measurement control.

Step 203. Traffic steering: The eNB/RNC sends the steering commandmessage to the UE to perform the traffic steering based on the reportedmeasurements and loading in the RAN.

The above procedures do not take into account user preference and/or theWLAN radio state. For example, based on user preferences and/or WLANradio state, a UE may not be able to perform the configured measurementevents. Additionally, the procedures need to allow a UE to be able toprioritize non-operator WLAN over operator WLAN. For example, the UE maydisassociate from the operator WLAN and associate with the higherpriority non-operator WLAN at any time during the measurement process.

The procedure illustrated above, and the following description can applyto UMTS CELL_FACH as well. The procedure can also be extended toUMTS/LTE Idle modes and UMTS CELL/URA_PCH states, e.g. UEs may beconfigured to report some indication (e.g. on available WLANmeasurements) in a RRC UL message, e.g., RRC connection request (fromIdle, in UMTS/LTE) or CELL UPDATE (in UMTS CELL/URA_PCH states).

Some of the steps above, e.g. steps 201 & 202, can be optional, based onRAN/UE configuration.

Step 201: Measurement Control—

For measurement control, the following examples are types of informationcan be configured for the UE to measure the operator WLAN:

1. Measurement events to trigger reporting as defined in Table 2 below2. Target identification as defined in Table 3 below 3. Measurements toreport as defined in Table 4 below

Based on the measurement events defined in 3GPP TS 36.331 [“EvolvedUniversal Terrestrial Radio Access (E-UTRA); Radio Resource Control(RRC); Protocol specification”] and 3GPP TS 25.331 [“Radio ResourceControl (RRC); Protocol Specification”], Table 2 shows the candidatemeasurement events for WLAN:

TABLE 2 Candidate measurement events for reporting WLAN EventDescription W1 WLAN becomes better than a threshold (to trigger trafficsteering to WLAN) W2 WLAN becomes worse than a threshold (to triggertraffic steering from WLAN) W3 3GPP Cell's radio quality becomes worsethan threshold1 and WLAN's radio quality becomes better than threshold2(to trigger traffic steering to WLAN) W4 WLAN's radio quality becomesworse than threshold1 and 3GPP Cell's radio quality becomes better thanthreshold2 (to trigger traffic steering from WLAN)

The thresholds are based on the values of the measurements to reportdefined in Table 4 below.

The target identification is used to indicate to the UE which WLAN toconsider for the measurement control procedures including the targetWLAN ID and the operating channels to search for. Table 3 shows thecandidate target identifiers for WLAN.

For steering traffic from WLAN, i.e., W2/W4, it may be sufficient thatjust the serving WLAN below a threshold is reported, i.e. the WLANtarget identifiers are not needed.

TABLE 3 Candidate target identifiers for WLAN Availability IdentifierDescription in WLAN BSSID Basic Service Set Identifier: For Beacon orProbe infrastructure BSS, the BSSID is Response the MAC address of thewireless access point SSID Service Set Identifier: The SSID Beacon orProbe can be used in multiple, possibly Response overlapping, BSSsHESSID Homogeneous Extended Service Set Beacon or Probe Identifier: AMAC address whose Response (802.11) value shall be configured by theHotspot Operator with the same value as the BSSID of one of the APs inthe network. All APs in the wireless network shall be configured withthe same HESSID value. Domain Domain Name List element provides ANQP(HS2.0) Name List a list of one or more domain names of the entityoperating the WLAN access network. Operating Indication of the targetWLAN N/A class, frequency. See Annex E of 802.11 channel [5] fordefinitions of the number different operating classes NOTE: If aboveinformation is not available in eNB/RNC, it is possible for RAN toconfigure general WLAN measurements

Step 202: Measurement Report—

Table 4 shows the candidate measurements to report for WLAN.

TABLE 4 Candidate measurement to report for WLAN Availability IdentifierDescription in WLAN RCPI Received Channel Power Indicator: MeasureMeasurement of the received RF power in the selected channel for areceived frame in the range of −110 to 0 dBm RSNI Received Signal toNoise Indicator: An Measurement indication of the signal to noise plusinterference ratio of a received IEEE 802.11 frame. Defined by the ratioof the received signal power (RCPI-ANPI) to the noise plus interferencepower (ANPI) in steps of 0.5 dB in the range from −10 dB to +117 dB BSSContains information on the current Beacon or Load STA population andtraffic levels in Probe the BSS. Response (802.11k) WAN Includesestimates of DL and UL speeds ANQP (HS metrics and loading as well aslink status and 2.0) whether the WLAN AP is at capacity.

Step 203: Traffic Steering—

In order for RAN to control traffic routing (if agreed to be supported)if ANDSF [Access Network Discovery and Selection Function] is not used,the RAN would need to know which APNs [Access Point Names]/bearers maybe (not) offloaded. The RAN also needs means to inform the UEsaccordingly so that e.g. the UE can issue the corresponding bindingupdate with the CN over S2c. This would impact signalling between CN andeNB as well as the UE behaviour between AS and NAS level. Table 5 showscandidate examples for identifying the traffic to steer to or from WLAN.

TABLE 5 Candidate identifiers of the traffic to steer to or from WLANIdentifier Description DRB/RB-ID Identity of a radio bearer QCI QoSClass Identifier

Establishing the Mapping Between Network Identifiers and Indices

In some embodiments the indices are numerical values. The index maytherefore be an integer value. Possible ranges are 0-15, 1-16, etc,although the range can depend on how many network identifiers there are.The mapping would then indicate the associated numerical value for eachWLAN identifier. One example how this mapping could be communicated froma network node 10 to a terminal device 12 in RRC is illustrated belowwhere the information element wlan-identifierindex indicates which indexthe associated identifier has:

WLAN-IDPerPLMN-r12 ::= SEQUENCE { wlan-Identifiers CHOICE { ssid OCTETSTRING (SIZE (1..32)), bssid OCTET STRING (SIZE (6)), hessid OCTETSTRING (SIZE (6)) }, wlan-identifierIndex INTEGER (1..maxWLAN-d-r12)OPTIONAL -- Need OR }

In some embodiments a default index will be assigned by a terminaldevice 12 or other network node 10 to a WLAN identifier for which thenetwork has not provided an index.

The index may then not need to be signaled to the terminal device 12 orthe other network node 10 and additional signaling overhead reductioncan be achieved. An example how this can be implemented in RRC is shownbelow where the value 0 is the default value for WLAN identifiers.

WLAN-IDPerPLMN-r12 ::= SEQUENCE { wlan-Identifiers CHOICE { ssid OCTETSTRING (SIZE (1..32)), bssid OCTET STRING (SIZE (6)), hessid OCTETSTRING (SIZE (6)) }, wlan-identifierIndex INTEGER (1..maxWLAN-d-r12)DEFAULT 0 }

This index may alternatively be an alphanumeric or alphabetic character.An example of how this can be implemented in RRC is shown below.

WLAN-IDPerPLMN-r12 ::= SEQUENCE { wlan-Identifiers CHOICE { ssid OCTETSTRING (SIZE (1..32)), bssid OCTET STRING (SIZE (6)), hessid OCTETSTRING (SIZE (6)) }, wlan-identifierIndex IA5String OPTIONAL -- Need OR}

In some embodiments the mapping is implicit, and it is not necessary fora network node to explicitly signal the mapping and index associatedwith each identifier since a terminal device 12 or other network node 10will implicitly know the index of an identifier. One possible way ofimplementing implicit mapping is for the index to be determined based onthe position of the network identifier in a list and/or sequence. Forexample, a list and/or sequence of WLAN identifiers can be indicated inthe following order: SSID A, SSID B, SSID C. The indices could then bemapped as: SSID A has index 1 (or 0), SSID B has index 2 (or 1), SSID Chas index 3 (or 2).

In some embodiments, the index can be signaled using a priorityindicator. The example below shows how a priority indicator can be used.The priority indicator would need to be signaled as a unique value foreach network identifier if it is to be possible to distinguish differentidentifiers (i.e. two WLAN identifiers cannot have the same priority).However, it would be possible for multiple WLAN identifiers to have thesame index (i.e. priority indicator in this embodiment) in case it isacceptable that the identifiers which share a priority indicator aretreated similarly (e.g. the network sends a traffic steering commandwhich targets multiple WLANs).

WLAN-IDPerPLMN-r12 ::= SEQUENCE { wlan-Identifiers CHOICE { ssid OCTETSTRING (SIZE (1..32)), bssid OCTET STRING (SIZE (6)), hessid OCTETSTRING (SIZE (6)) }, wlan-Priority INTEGER (1..maxWLAN-Id-r12), OPTIONAL-- Need OR }

In some embodiments the same index may be assigned to multiple networkidentifiers. This could be done for networks or network nodes that donot need to be treated or considered differently (for example in anaccess network selection and/or traffic steering mechanism). Forexample, if in a certain situation WLAN A and WLAN B can be treatedsimilarly those identifiers could be assigned the same index. However iftwo WLANs should be treated differently, then different indices could beassigned to the two WLANs (for example if one WLAN belongs to theoperator and the other WLAN belongs to the operator's partner and maycost more to use, then the operator may want to treat the WLANsdifferently and hence assign different indices to the two WLANs).

In some embodiments multiple indices can be assigned to a networkidentifier. This allows a WLAN identifier to be assigned one index whichis common for multiple WLAN identifiers while also being assigned anindex which is unique to that WLAN identifier (or common to a smallergroup of identifiers). The benefit of this in an access networkselection and/or traffic steering mechanism is that the network 10 andterminal device 12 may use the index that is common for multiple WLANidentifiers (i.e. a low granular index) in situations where it is notimportant to distinguish those WLAN identifiers, while one uniqueidentifier could also be indicated by using a unique index (i.e. a highgranular index). For example, consider a scenario where the trafficsteering command based mechanism described above is used and the networkwants to perform offloading to WLAN for a terminal device. The networkmay then request the terminal device 12 perform measurements of multipleWLANs by using the low granular index (so that multiple WLANs aremeasured). The terminal device 12 would then report back to the networkin a measurement report; however in this measurement report it may beimportant to get measurements per WLAN identifier and hence the terminaldevice 12 could report the measurements and indicate the high granularindex.

Example 1 below shows one possible identifier-to-index mapping. In thisexample there are two identifiers (BSSID V and BSSID W) which have thesame index. This may be used for example if the two WLAN identifiershave some commonality such as belonging to the same SSID. The networkmay not need to distinguish between BSSID V and BSSID W if these belongto the same SSID. Example 1 also shows how each identifier can havemultiple indices (indicated by the additional index in the Index2column).

Example 1: WLAN identifier to index mapping WLAN identifier Index1Index2 BSSID U 1 A BSSID V 2 B BSSID W 2 C SSID X 3 D SSID Y 6 E

The mapping may be signaled to a terminal device 12 by a RAN node 10using broadcast signaling. Signaling the mapping with broadcastsignaling will ensure that it does not need to be signaled to eachterminal device 12 that needs to receive it, hence radio resources maybe saved.

Alternatively, the mapping may be signaled to the terminal device 12using dedicated signaling. The benefit of using dedicated signaling isthat different terminal devices may be provided with differentidentifier-to-index mappings which could allow for differentiation ofterminal devices 12.

In some embodiments the mapping can be signaled to a terminal device 12by a core network node 6 such as an MME. The MME 6 can then inform theterminal device 12 of the mapping using non-access stratum (NAS)signaling. The MME 6 may also signal this mapping to the RAN node 10(e.g. to an eNB over the S1-interface) so that the RAN node 10 caninterpret a communication (e.g. a measurement report) containing indicesreceived from the terminal device 12.

In some embodiments the identifier to index mapping can be preconfiguredin the terminal device 12. One example is that the indices and mappingis provided to the terminal device 12 on a subscriber identity module(SIM)-card or similar entity. Network nodes (e.g. in the RAN) could thenbe informed of the appropriate mapping, for example by operationsadministration and management (OAM) configuration.

When the identifier-to-index mapping has been established and providedto the terminal device 12 and/or RAN node 10 the mapping can be used toreduce the amount of signaling between the terminal device 12 and thenetwork 2 or between network nodes 10 in the network 2. The followingsection provides some examples of how the identifier-to-index mappingcan be used.

Uses of WLAN Identifiers

In some embodiments the terminal device 12 or network node 10 will, whensending a message to another node (e.g. network node 10 or terminaldevice 12) in which a WLAN identifier should be conveyed, include theindex (or indices) associated with the WLAN identifier instead of e.g.reporting the identifier itself. For example, a terminal device 12 couldbe configured to report to the network the indices of WLANs for whichone or more criteria are fulfilled. Example criteria can include:

-   -   A WLAN has been detected.    -   One or more measured signal metrics of a WLAN node 14 are above        (or below) thresholds.    -   The load and/or capacity of a WLAN node 14 is above (or below) a        threshold.

For example, the terminal device 12 can be configured to report to the3GPP RAN when it has detected WLAN APs with an SSID X, and the terminaldevice 12 would then report the index associated with SSID X, e.g. 3and/or D (as indicated in Example 1 above). In another example, theterminal device 12 may have measured (or received an indication of) thata WLAN with BSSID V has, for example, a load level below 40% and ameasured signal strength above 60 dBm, and the terminal device 12 wouldthen report index 2 and/or C (2 and C being the indices for BSSID V inExample 1).

One WLAN AP 14 can have identifiers of different types. For example, aWLAN AP 14 could have an SSID X and a BSSID U. In some embodiments, theterminal device 12 will report the index associated with only oneidentifier associated with a WLAN. For example, if a WLAN node 14 hasSSID X with index 3 and has a BSSID U with index 1 the terminal device12 may be configured to only report either 3 or 1. Which of the multipleindices are to be reported may, for example, be decided based on thetype of identifiers. Since BSSIDs are of higher granularity (associatedwith a specific WLAN node 14) while SSIDs have lower granularity(associated with a group of WLAN APs 14) it would provide moreinformation to the network if the terminal device 12 reports that hasdetected a certain BSSID instead of detecting a certain SSID, i.e. theUE would in the example above report index ‘1’. It would also bepossible for the network to configure the terminal device 12 as to whichindex the terminal device 12 should apply. In an alternative embodimentthe terminal device 12 can report all applicable indices for a WLAN.Using the example above, the terminal device 12 would then report bothindices ‘3’ and ‘1’.

In case multiple WLANs that share an index meet the criteria for sendinga measurement report, the terminal device 12 may include in the reportinformation related to one of the multiple WLANs. For example, if theterminal device 12 measures BSSID V and BSSID W and both fulfills acriterion for reporting, then the UE 12 may only include in the reportinformation/measurements relating to one of BSSID V and BSSID W. Whichof the multiple WLANs is included may be configured by the network, e.g.by an associated priority.

In some embodiments, the terminal device 12 can indicate to the networkhow many WLANs matching a certain index fulfill the reporting condition.For example, if the conditions for reporting for BSSID U, BSSID V andBSSID W are fulfilled the terminal device 12 may report index 1 andindex 2 (as in Example 1 above). But the terminal device 12 may thenaccording to this embodiment also indicate that there is one nodeassociated with index 1 for which the conditions are fulfilled, and twonodes associated with index 2 for which the conditions are fulfilled.

In some embodiments, the network (e.g. 3GPP RAN) may indicate to theterminal device 12 that it is to perform a mobility-related proceduretowards a WLAN by signaling the associated index. A mobility-relatedprocedure may be one or many of measurement reporting, traffic steering,access selection, traffic aggregation, etc. Prior to this being done thenetwork would need to indicate the identifier to index mapping, asdiscussed above. For example, the network may indicate to the terminaldevice 12 that it is to steer traffic to a WLAN with index 1, and the UE12 would then (according to the example mapping in Example 1 above)steer traffic to the WLAN with BSSID U. If the network indicates to theterminal device 12 to aggregate traffic over WLAN (and 3GPP) with index2 then the UE 12 may aggregate traffic over WLAN with BSSID V or BSSID Wand over 3GPP.

As noted above, it is also possible for the identifier-to-index mappingto be used in other messages/indications/procedures than those describedabove. For example, another use case for the identifier-to-index mappingis when the network indicates that a terminal device 12 should evaluatean access network selection, traffic steering and/or carrier aggregationmechanism considering only certain WLAN identifiers.

Indication of Whether to Use Indices or Network Identifiers

Not all terminal devices, networks, or network nodes, may be capable ofusing indices instead of network identifiers. Therefore the networkcould, in some embodiments, indicate to the terminal device 12 whetherto use indices or to use WLAN identifiers when referring to WLANs. Forexample, if an LTE eNB is capable of using indices instead of WLANidentifiers, that eNB may indicate to the terminal devices 12 it isserving that signalling of indices should be used, while if another LTEeNB is not capable of using indices instead of WLAN identifiers thenthat eNB may indicate to the terminal device 12 that signalling of WLANidentifiers should be used.

The indication may be explicitly signalled by the network, for exampleas a bit-flag indication, which could be signalled using dedicatedsignalling or broadcast signalling. It may be the case that if thisbit-flag has not been signalled to the terminal device 12, the terminaldevice 12 would interpret this as the network indicating that indicesshould not be used.

In some embodiments it is possible for this indication to be signalledimplicitly. The terminal device 12 may consider that the network hasindicated that indices should be used if the network signals indicestogether with the WLAN identifiers, while if the network has notindicated any indices with the WLAN identifiers, the terminal device 12would consider that the network has indicated that indices should not beused.

Specific Embodiment

The flow chart in FIG. 10 illustrates a specific embodiment of thetechniques described herein in which an identifier to index mapping isused in a traffic steering command based approach to an access networkselection and/or traffic steering. The steps shown in FIG. 10 coversteps performed in both the terminal device and the network (e.g. RAN)node.

Thus, in step 301 a terminal device 12 receives a WLAN identifier toindex mapping over broadcast signalling from an eNB 10. The terminaldevice 12 maintains the mapping (step 303), for example by storing it ina memory unit.

As part of an access network selection and/or traffic steeringprocedure, the terminal device 12 is requested by the eNB 10 to performmeasurement reporting of a WLAN with an index X (step 305).

The terminal device 12 extracts the WLAN identifier(s) associated withindex X from the mapping (step 307) and performs measurements of WLANshaving identifier(s) matching the extracted identifier(s) (step 309).

The terminal device 12 constructs a measurement report and indicates theindices for the measured WLANs in the report (step 311). The report issent to the eNB 10.

The network (eNB 10) receives the measurement report (step 313).

The network extracts from the identifier to index mapping the WLANidentifiers corresponding to the indices in the received report (step315).

The network then evaluates whether the terminal device 12 should steertraffic to the reported WLANs and if so to which WLAN (step 317). If notraffic steering is to be performed, the method ends (steps 319 and321). If traffic steering is to be performed, the network indicates tothe terminal device 12 that traffic steering should be performed (via atraffic steering command) and includes the index of the WLAN to whichtraffic should be steered (step 323).

The terminal device 12 receives the indication (traffic steeringcommand) and extracts the WLAN identifier associated with the indicatedindex from the identifier to index mapping (step 325). The terminaldevice 12 then performs the traffic steering to the appropriate WLAN(step 327).

Modifications and other variants of the described embodiment(s) willcome to mind to one skilled in the art having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the embodiment(s)is/are not to be limited to the specific examples disclosed and thatmodifications and other variants are intended to be included within thescope of this disclosure. Although specific terms may be employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

Various exemplary embodiments of the techniques described herein are setout below:

1. A method of operating a terminal device, the method comprising:

-   -   maintaining one or more indices and a mapping between the one or        more indices and respective network identifiers, each network        identifier identifying a network or a network node; and    -   in communications between the terminal device and a first        network in which a particular network or a particular network        node is to be identified, using the index associated with the        particular network or the particular network node to identify        the particular network or the particular network node.

2. A method as in embodiment 1, wherein the step of using comprisesincluding the index in a message sent from the terminal device to thefirst network to identify the particular network or the particularnetwork node to the first network.

3. A method as in embodiment 1 or 2, wherein the method furthercomprises the step of receiving a message from the first network, themessage comprising an index; and the step of using comprises using theindex in the received message and the mapping to identify a particularnetwork or a particular network node.

4. A method as in embodiment 1, 2 or 3, wherein communications betweenthe terminal device and the first network comprise at least one ofuplink communications from the terminal device to the first network anddownlink communications from the first network to the terminal device.

5. A method as in any of embodiments 1-4, wherein each networkidentifier identifies a network other than the first network or anetwork node in a network other than the first network.

6. A method as in embodiment 5, wherein the network other than the firstnetwork is a network that is operating according to a different radioaccess technology, RAT, to the first network.

7. A method as in any of embodiments 1-6, wherein the first network is anetwork operating according to a mobile telecommunications radio accesstechnology, RAT, and the particular network or the particular networknode are operating according to a wireless local area network RAT.

8. A method as in embodiment 7, wherein the mobile telecommunicationsRAT is a 3GPP-specified RAT.

9. A method as in embodiment 7 or 8, wherein the wireless local areanetwork RAT is WLAN or Wi-Fi.

10. A method as in any of embodiments 1-9, wherein each networkidentifier is an identifier of a WLAN or a network node in a WLAN.

11. A method as in any of embodiments 1-10, wherein at least one networkidentifier is an identifier for an access point, AP, in a WLAN.

12. A method as in any of embodiments 1-11, wherein at least one networkidentifier is a service set identification, SSID, a basic SSID, BSSID,an extended SSID, ESSID, a homogenous ESSID, HESSID, Realm identifier, aNetwork Access Indicator, NAI, a public land mobile network, PLMNidentifier, or a Domain Name list.

13. A method as in any of embodiments 1-12, the method furthercomprising the step of:

-   -   receiving the one or more indices and the mapping between the        one or more indices and respective network identifiers from the        first network.

14. A method as in embodiment 13, wherein the one or more indices andthe mapping between the one or more indices and respective networkidentifiers are received from the first network in broadcast signallingand/or dedicated signalling.

15. A method as in embodiment 13 or 14, wherein the one or more indicesand the mapping between the one or more indices and respective networkidentifiers are received from a network node in the radio accessnetwork, RAN, of the first network.

16. A method as in embodiment 13, wherein the one or more indices andthe mapping between the one or more indices and respective networkidentifiers are received from a core network node in the first network.

17. A method as in embodiment 16, wherein the one or more indices andthe mapping between the one or more indices and respective networkidentifiers are received from a core network node in the first networkin non-access stratum, NAS, signalling.

18. A method as in any of embodiments 1-17, the method furthercomprising the steps of:

-   -   receiving a list and/or sequence of one or more network        identifiers from the first network; and    -   determining the one or more indices and mapping between the one        or more indices and the one or more network identifiers based on        the position of each network identifier in the received list        and/or sequence.

19. A method as in any of embodiments 1-18, wherein each index comprisesa numerical value or an alphanumerical value.

20. A method as in any of embodiments 1-19, wherein the index issignalled using a priority value in communications between the terminaldevice and the first network.

21. A method as in any of embodiments 1-20, wherein a default value foran index is used in communications between the terminal device and thefirst network for a network identifier that is not included in themapping.

22. A method as in any of embodiments 1-21, wherein two or more networksor network nodes have the same index.

23. A method as in embodiment 22, wherein in the event that at least oneof the networks or network nodes having the same index is to beidentified in communications between the terminal device and the firstnetwork, the communications between the terminal device and the firstnetwork further comprise an indication of how many of said networks ornetwork nodes having the same index the communications apply to.

24. A method as in any of embodiments 1-23, wherein a network identifierhas two or more associated indices.

25. A method as in embodiment 24, wherein the method further comprisesthe step of:

-   -   for a network identifier that has two or more associated        indices, determining an action to take with respect to the        particular network or the particular network node identified by        the network identifier based on which of the two or more indices        associated with the network identifier has been received from        the first network.

26. A method as in any of embodiments 1-25, wherein a particular networkor a particular network node has two or more associated networkidentifiers, each network identifier having a respective index, and incommunications between the network node and a terminal device in whichthe particular network or particular network node having the two or moreassociated network identifiers is to be identified, the step of usingcomprises using one or more of the indices to identify the particularnetwork or the particular network node.

27. A method as in embodiment 26, wherein the two or more associatednetwork identifiers are different types of network identifiers, and thestep of using comprises using an index for a specific type of networkidentifier to identify the particular network or the particular networknode.

28. A method as in any of embodiments 1-27, wherein the method furthercomprises the step of receiving an indication from the first network ofwhether the terminal device is to use network identifiers or indices toidentify particular networks or particular network nodes incommunications between the terminal device and the first network.

29. A method as in any of embodiments 1-28, wherein communicationsbetween the terminal device and the first network comprisecommunications relating to an access network selection, traffic steeringand/or traffic aggregation procedure.

30. A method as in any of embodiments 1-29, wherein communicationsbetween the terminal device and the first network comprisecommunications relating to an access network selection, traffic steeringand/or traffic aggregation procedure between the first network and asecond network operating according to a different radio accesstechnology, RAT, to the first network.

31. A method as in embodiment 30, wherein each network identifieridentifies a particular second network or a particular network node inthe second network.

32. A terminal device, wherein the terminal device is adapted to:

-   -   maintain one or more indices and a mapping between the one or        more indices and respective network identifiers, each network        identifier identifying a network or a network node; and    -   use the index associated with the particular network or the        particular network node to identify the particular network or        the particular network node in communications between the        terminal device and a first network in which a particular        network or a particular network node is to be identified.

Various other embodiments of the terminal device are contemplated inwhich the terminal device is further adapted to operate according to anyof the above method embodiments.

33. A method of operating a network node in a first network, the methodcomprising:

-   -   maintaining one or more indices and a mapping between the one or        more indices and respective network identifiers, each network        identifier identifying a network or a network node; and    -   in communications between the network node and a terminal device        or other network node in which a particular network or a        particular network node is to be identified, using the index        associated with the particular network or the particular network        node to identify the particular network or the particular        network node.

34. A method as in embodiment 33, wherein the step of using comprisesincluding the index in a message sent to the terminal device or othernetwork node from the network node to identify the particular network orthe particular network node to the terminal device or other networknode.

35. A method as in embodiment 33 or 34, wherein the method furthercomprises the step of receiving a message from the terminal device orother network node, the message comprising an index; and the step ofusing comprises using the index in the received message and the mappingto identify a particular network or a particular network node.

36. A method as in embodiment 33, wherein communications between theterminal device and the first network comprise at least one of uplinkcommunications from the terminal device to the network node and downlinkcommunications from the network node to the terminal device.

37. A method as in any of embodiments 33-36, wherein each networkidentifier identifies a network other than the first network or anetwork node in a network other than the first network.

38. A method as in embodiment 37, wherein the network other than thefirst network is a network that is operating according to a differentradio access technology, RAT, to the first network.

39. A method as in any of embodiments 33-38, wherein the first networkis a network operating according to a mobile telecommunications radioaccess technology, RAT, and the particular network or the particularnetwork node are operating according to a wireless local area networkRAT.

40. A method as in embodiment 39, wherein the mobile telecommunicationsRAT is a 3GPP-specified RAT.

41. A method as in embodiment 39 or 40, wherein the wireless local areanetwork RAT is WLAN or Wi-Fi.

42. A method as in any of embodiments 33-41, wherein each networkidentifier is an identifier of a WLAN or a network node in a WLAN.

43. A method as in any of embodiments 33-42, wherein at least onenetwork identifier is an identifier for an access point, AP, in a WLAN.

44. A method as in any of embodiments 33-43, wherein at least onenetwork identifier is a service set identification, SSID, a basic SSID,BSSID, an extended SSID, ESSID, a homogenous ESSID, HESSID, Realmidentifier, a Network Access Indicator, NAI, a public land mobilenetwork, PLMN identifier, or a Domain Name list.

45. A method as in any of embodiments 33-44, wherein the method furthercomprises the step of:

-   -   determining the one or more indices and the mapping between the        one or more indices and the respective network identifiers.

46. A method as in any of embodiments 33-45, wherein the method furthercomprises the step of:

-   -   receiving the one or more indices and the mapping between the        one or more indices and the respective network identifiers from        a network node in the radio access network, RAN, of the first        network or a network node in the core network of the first        network.

47. A method as in any of embodiments 33-46, wherein the method furthercomprises the step of:

-   -   sending the one or more indices and the mapping between the one        or more indices and respective network identifiers to the        terminal device or other network node.

48. A method as in embodiment 47, wherein the one or more indices andthe mapping between the one or more indices and respective networkidentifiers are sent to the terminal device in broadcast signalling ordedicated signalling.

49. A method as in any of embodiments 33-48, wherein the method furthercomprises the steps of:

-   -   sending a list and/or sequence of one or more network        identifiers to the terminal device or other network node; and    -   determining one or more indices and mapping between the one or        more indices and the one or more network identifiers based on        the position of each network identifier in the sent list and/or        sequence.

50. A method as in any of embodiments 33-49, wherein each indexcomprises a numerical value or an alphanumerical value.

51. A method as in any of embodiments 33-50, wherein the index issignalled using a priority value in communications between the networknode and the terminal device or other network node.

52. A method as in any of embodiments 33-51, wherein a default value foran index is used in communications between the network node and terminaldevice or other network node for a network identifier that is notincluded in the mapping.

53. A method as in any of embodiments 33-52, wherein two or morenetworks or network nodes have the same index.

54. A method as in embodiment 53, wherein in the event that at least oneof the networks or network nodes having the same index is to beidentified in communications between the network node and the terminaldevice or other network node, the communications between the networknode and the terminal device or other network node further comprise anindication of how many of said networks or network nodes having the sameindex the communications apply to.

55. A method as in any of embodiments 33-54, wherein a networkidentifier has two or more associated indices.

56. A method as in embodiment 55, wherein the method further comprisesthe steps of:

-   -   for each of the two or more indices associated with a network        identifier, associating an action for the terminal device or        other network node to take with respect to the particular        network or the particular network node;    -   determining an action for the terminal device or other network        node to take with respect to the particular network or the        particular network node identified by the network identifier;        and    -   using the index associated with the determined action in        communications with the terminal device or other network node to        cause the terminal device or other network node to take the        determined action with respect to the particular network or the        particular network node.

57. A method as in any of embodiments 33-56, wherein a particularnetwork or a particular network node has two or more associated networkidentifiers, each network identifier having a respective index, and incommunications between the network node and a terminal device or othernetwork node in which the particular network or particular network nodehaving the two or more associated network identifiers is to beidentified, the step of using comprises using one or more of the indicesto identify the particular network or the particular network node.

58. A method as in embodiment 57, wherein the two or more associatednetwork identifiers are different types of network identifiers, and thestep of using comprises using an index for a specific type of networkidentifier to identify the particular network or the particular networknode.

59. A method as in any of embodiments 33-58, wherein the method furthercomprises the step of sending an indication to the terminal device orother network node indicating whether the terminal device or othernetwork node is to use network identifiers or indices to identifyparticular networks or particular network nodes in communicationsbetween the network node and the terminal device or other network node.

60. A method as in any of embodiments 32-59, wherein the communicationscomprise communications with the terminal device relating to an accessnetwork selection, traffic steering and/or traffic aggregationprocedure.

61. A method as in any of embodiments 32-59, wherein the communicationscomprise communications with the terminal device relating to an accessnetwork selection, traffic steering and/or traffic aggregation procedurebetween the first network and a second network operating according to adifferent radio access technology, RAT, to the first network.

62. A method as in any of embodiments 61, wherein each networkidentifier identifies a particular second network or a particularnetwork node in the second network.

63. A network node for use in a first network, wherein the network nodeis adapted to maintain one or more indices and a mapping between the oneor more indices and respective network identifiers, each networkidentifier identifying a network or a network node; and use the indexassociated with the particular network or the particular network node toidentify the particular network or the particular network node incommunications between the network node and a terminal device or othernetwork node in which a particular network or a particular network nodeis to be identified.

Various other embodiments of the network node are contemplated in whichthe network node is further adapted to operate according to any of theabove method embodiments.

64. A method of operating a network node in a first network, the methodcomprising:

-   -   determining one or more indices and a mapping between the one or        more indices and respective network identifiers, each network        identifier identifying a network or a network node; and    -   sending the one or more indices and the mapping to another        network node in the first network or to a terminal device in the        first network.

65. A method as in embodiment 64, wherein each network identifieridentifies a network other than the first network or a network node in anetwork other than the first network.

66. A method as in embodiment 65, wherein the network other than thefirst network is a network that is operating according to a differentradio access technology, RAT, to the first network.

67. A method as in any of embodiments 64-66, wherein the first networkis a network operating according to a mobile telecommunications radioaccess technology, RAT, and the particular network or the particularnetwork node are operating according to a wireless local area networkRAT.

68. A method as in embodiment 67, wherein the mobile telecommunicationsRAT is a 3GPP-specified RAT.

69. A method as in embodiment 67 or 68, wherein the wireless local areanetwork RAT is WLAN or Wi-Fi.

70. A method as in any of embodiments 64-69, wherein each networkidentifier is an identifier of a WLAN or a network node in a WLAN.

71. A method as in any of embodiments 64-71, wherein at least onenetwork identifier is an identifier for an access point, AP, in a WLAN.

72. A method as in any of embodiments 64-71, wherein at least onenetwork identifier is a service set identification, SSID, a basic SSID,BSSID, an extended SSID, ESSID, a homogenous ESSID, HESSID, Realmidentifier, a Network Access Indicator, NAI, a public land mobilenetwork, PLMN identifier, or a Domain Name list.

73. A method as in any of embodiments 64-72, wherein the network node isa node in the core network of the first network, and the step of sendingcomprises sending the one or more indices and the mapping to a terminaldevice in the first network using non-access stratum, NAS, signalling.

74. A method as in any of embodiments 64-73, wherein each indexcomprises a numerical value or an alphanumerical value.

75. A method as in any of embodiments 64-74, wherein two or morenetworks or network nodes have the same index.

76. A method as in any of embodiments 64-75, wherein a networkidentifier has two or more associated indices.

77. A method as in any of embodiments 64-76, wherein the network node isa network node in the core network of the first network.

78. A network node for use in a first network, the network node beingadapted to determine one or more indices and a mapping between the oneor more indices and respective network identifiers, each networkidentifier identifying a network or a network node; and send the one ormore indices and the mapping to another network node in the firstnetwork or to a terminal device in the first network.

Various other embodiments of the network node are contemplated in whichthe network node is further adapted to operate according to any of theabove method embodiments.

79. A computer program product comprising a computer readable mediumhaving computer readable code embodied therein, the computer readablecode being configured such that, on execution by a suitable computer orprocessor, the computer or processor is caused to perform any of themethod embodiments described above.

1-56. (canceled)
 57. A method of operating a terminal device, the methodcomprising: maintaining one or more indices and a mapping between theone or more indices and respective network identifiers, each networkidentifier identifying a different network node; in communicationsbetween the terminal device and a first network, using the one or moreindices to identify at least one network node; and for a first indexbeing mapped to two or more network identifiers, signaling, in thecommunications, a number of network nodes that correspond to the firstindex.
 58. The method of claim 57, wherein using the one or more indicesto identify at least one network node comprises: sending, to the atleast one network node in the first network, a message comprising theone or more indices.
 59. The method of claim 57, further comprising:receiving a message from the first network, the message comprising theone or more indices; and using the one or more indices and the mappingto identify the at least one network node.
 60. The method of claim 57,wherein the communications between the terminal device and the firstnetwork comprise at least one of: uplink communications from theterminal device to the first network or downlink communications from thefirst network to the terminal device.
 61. The method of claim 57,wherein using the one or more indices to identify at least one networknode comprises: using the one or more indices to identify at least onenetwork node in a second network that operates according to a differentradio access technology (RAT) than the first network.
 62. The method ofclaim 61, wherein the first network operates according to a mobiletelecommunications RAT, and the second network operates according to awireless local area network RAT.
 63. The method of claim 62, wherein themobile telecommunications RAT is a 3GPP-specified RAT.
 64. The method ofclaim 62, wherein the wireless local area network RAT is WLAN or Wi-Fi.65. The method of claim 57, wherein at least one network identifiercomprises: a service set identification (SSID), a basic SSID (BSSID), anextended SSID (ESSID), a homogenous ESSID (HESSID), a Realm identifier,a Network Access Indicator (NAI), a public land mobile network (PLMN)identifier, or a Domain Name list.
 66. The method of claim 57, furthercomprising: receiving the one or more indices and the mapping betweenthe one or more indices and respective network identifiers from thefirst network.
 67. The method of claim 66, further comprising: receivingthe one or more indices and the mapping from the first network inbroadcast signaling or dedicated signaling.
 68. The method of claim 66,further comprising: receiving the one or more indices and the mappingfrom a network node in a radio access network (RAN) of the firstnetwork.
 69. The method of claim 66, further comprising: receiving theone or more indices and the mapping from a core network node in thefirst network.
 70. The method of claim 69, further comprising: receivingthe one or more indices and the mapping from the core network node innon-access stratum (NAS) signaling.
 71. The method of claim 57, whereineach of the one or more indices comprises a numerical value or analphanumerical value.
 72. The method of claim 57, further comprising:signaling, in the communications between the terminal device and thefirst network, the one or more indices using a priority value.
 73. Themethod of claim 57, further comprising: receiving, from the firstnetwork, an indication of whether the terminal device is to use anetwork identifier or an index to identify a network node incommunications between the terminal device and the first network. 74.The method of claim 57, wherein the communications between the terminaldevice and the first network comprise at least one of: communicationsrelating to an access network selection, traffic steering, or trafficaggregation procedure.
 75. A terminal device, comprising: a memorystoring instructions; and a processor configured to execute theinstructions to: maintain one or more indices and a mapping between theone or more indices and respective network identifiers, each networkidentifier identifying a different network node; in communicationsbetween the terminal device and a first network, use the one or moreindices to identify at least one network node; and for a first indexbeing mapped to two or more network identifiers, signal, in thecommunications, a number of network nodes that correspond to the firstindex.
 76. A non-transitory computer-readable medium comprising acomputer program code that, when executed by a processor coupled to aterminal device, causes the terminal device to perform operationscomprising: maintaining one or more indices and a mapping between theone or more indices and respective network identifiers, each networkidentifier identifying a different network node; in communicationsbetween the terminal device and a first network, using the one or moreindices to identify at least one network node; and for a first indexbeing mapped to two or more network identifiers, signaling, in thecommunications, a number of network nodes that correspond to the firstindex.